Is it possible to use the public network, namely Internet, to make 2 machines communicate securely ? And if possible something easier to install and configure than OpenVpn ?
A few months ago, I heard about Nebula from Defined and wanted to test it : one single binary, some certificates and as secure as it can be, that sounded promising !
So here we are trying to simulate a mesh network between 2 virtual machines using Vagrant on my Ubuntu Linux distribution 20.04 with Virtualbox already installed.
Vagrant
Vagrant from Hashicorp is the tool I use to manage virtual machines.
1sudo apt install -y vagrant
I configure Vagrant to have 2 virtual machines with Debian 11, named respectively boxA and boxB.
To make it simple, I use my host network interface to link the 2 virtual machines (so eth0 in my case) and use the available DHCP of my local network.
1cat <<EOF > Vagrantfile
2Vagrant.configure("2") do |config|
3 config.vm.define "boxA" do |boxA|
4 boxA.vm.box = "generic/debian11"
5 boxA.vm.network "public_network", bridge: "eth0"
6 end
7 config.vm.define "boxB" do |boxB|
8 boxB.vm.box = "generic/debian11"
9 boxB.vm.network "public_network", bridge: "eth0"
10 end
11end
12EOF
Now I can launch the 2 machines with a single command :
1vagrant up
Nebula
Installing nebula is as simple as downloading the binaries from github. I choose nebula-linux-amd64.tar.gz to comply to my configuration.
1wget https://github.com/slackhq/nebula/releases/download/v1.6.0/nebula-linux-amd64.tar.gz
After downloading, I uncompress the archive :
tar xf nebula-linux-amd64.tar.gz
I now have 2 binaries : nebula and nebula-cert.
nebulawill be copied on the 2 virtual machines. This is the main binary who will establish the bridge between the machines.nebula-certwill be used to generate all needed certificates :
1./nebula-cert ca -name "ACME, Inc"
2./nebula-cert sign -name "boxA" -ip "192.168.168.100/24"
3./nebula-cert sign -name "boxB" -ip "192.168.168.200/24"
I choose 192.168.168.* as my mesh network IP addresses : .100 for boxA and .200 for boxB.
The results of the commands are this list of files :
1ca.crt
2ca.key
3boxA.crt
4boxA.key
5boxB.crt
6boxB.key
To make it more simple to copy the files to the virtual machines, I create a folder per machine and copy the needed files :
1mkdir boxA boxB
2mv boxA.* boxA && mv boxB.* boxB
Now I want to generate a Nebula configuration file, that will be common for the 2 machines. I need to get their IP addresses on my local network (those assigned by my DHCP server). I know that vagrant will use the eth1 interface inside the machines, so I use some magic shell script :
First on boxA :
1boxAip=$(vagrant ssh boxA --no-tty -c "ip address show eth1| grep 'inet ' | sed -e 's/^.*inet //' -e 's/\/.*$//'" | tr -d '\r')
Then on boxB :
1boxBip=$(vagrant ssh boxB --no-tty -c "ip address show eth1| grep 'inet ' | sed -e 's/^.*inet //' -e 's/\/.*$//'" | tr -d '\r')
The magic is that $boxAip and $boxBip variables now contain the wanted IPs. Let use them inside the Nebula config in the static_host_map section :
1cat <<EOF > config.yml
2pki:
3 ca: /etc/nebula/ca.crt
4 cert: /etc/nebula/host.crt
5 key: /etc/nebula/host.key
6static_host_map:
7 "192.168.168.100": ["$boxAip:4242"]
8 "192.168.168.200": ["$boxBip:4242"]
9lighthouse:
10 am_lighthouse: false
11listen:
12 host: 0.0.0.0
13 port: 4242
14punchy:
15 punch: true
16tun:
17 disabled: false
18 dev: nebula1
19 drop_local_broadcast: false
20 drop_multicast: false
21 tx_queue: 500
22 mtu: 1300
23 routes:
24 unsafe_routes:
25logging:
26 level: info
27 format: text
28firewall:
29 conntrack:
30 tcp_timeout: 12m
31 udp_timeout: 3m
32 default_timeout: 10m
33 max_connections: 100000
34 outbound:
35 - port: any
36 proto: any
37 host: any
38 inbound:
39 - port: any
40 proto: any
41 host: any
42EOF
It’s time to configure the machines. First, let send all the files to each machine :
1vagrant upload ./boxA /tmp/ boxA
2vagrant upload ./boxB /tmp/ boxB
3vagrant upload ca.crt /tmp/ boxA
4vagrant upload ca.crt /tmp/ boxB
5vagrant upload config.yml /tmp/ boxA
6vagrant upload config.yml /tmp/ boxB
7vagrant upload nebula /tmp/ boxA
8vagrant upload nebula /tmp/ boxB
Now I ssh in each machine and continue the configuration :
First, boxA :
1vagrant ssh boxA
Inside boxA, I move the files in their respective location and finally launch Nebula in the background before quitting boxA :
1sudo mkdir /etc/nebula
2sudo mv /tmp/config.yml /etc/nebula/config.yml
3sudo mv /tmp/ca.crt /etc/nebula/ca.crt
4sudo mv /tmp/boxA.crt /etc/nebula/host.crt
5sudo mv /tmp/boxA.key /etc/nebula/host.key
6sudo mkdir /opt/nebula
7sudo mv /tmp/nebula /opt/nebula/
8chmod +x /opt/nebula/nebula
9cd /opt/nebula
10sudo ./nebula -config /etc/nebula/config.yml &
11exit
Let’s configure boxB,
1vagrant ssh boxB
Then I move all files and launch Nebula :
1sudo mkdir /etc/nebula
2sudo mv /tmp/config.yml /etc/nebula/config.yml
3sudo mv /tmp/ca.crt /etc/nebula/ca.crt
4sudo mv /tmp/boxB.crt /etc/nebula/host.crt
5sudo mv /tmp/boxB.key /etc/nebula/host.key
6sudo mkdir /opt/nebula
7sudo mv /tmp/nebula /opt/nebula/
8chmod +x /opt/nebula/nebula
9cd /opt/nebula
10sudo ./nebula -config /etc/nebula/config.yml &
11exit
Ok, at this moment, I have 2 virtual machines, with a Nebula network between them. How am I going to verify that it is really working ?
Well if I can ping boxB from boxA, it will mean that all is ok, so let’s found out :
1vagrant ssh boxA -c "ping 192.168.168.200"
Hourra ! It is working. Of course, I can do it on the other side :
1vagrant ssh boxB -c "ping 192.168.168.100"
And that’s all folks for part 1 !
Next, I’ll try to use this configuration to execute a MySQL server on one machine, and access it from a MySQL client on the other machine. And to make it a little more difficult, I’ll use Podman as the container engine to execute this client and server.